University scavenges for gold in the delta
The University of Hong Kong has teamed up with a listed company in a research project to scavenge gold and silver residue from effluents discharged by factories in the Pearl River Delta.
The $1.8 million project, partially funded by the government's Innovation and Technology Fund, aims to deliver an industrial wastewater treatment system that is more effective and cheaper than conventional systems.
The research partner, Ocean Grand Chemicals Holdings, hopes the cheaper system can be made widely available throughout the mainland.
The company has a subsidiary, Kenlap PGC Manufacturer, which produces gold and silver salts for factories. In a 2002 study commissioned by the Hong Kong Productivity Council, factories in the delta region were found to consume an estimated 60,000kg of gold and 120,000kg of silver in industrial processes such as electroplating.
A mere 0.5 per cent recovery of these precious metals could yield $20 million worth of metals that could be recycled, the study found.
Chan Kwong-yu, a chemistry professor at the university, said there was an average of at least 10 milligrams of precious metals in a litre of industrial effluent generated from electroplating process.
The new process, using polymers instead of conventional resin to bind the metals, could increase the extraction efficiency by around 100 times, leaving unextracted residues in the water lower than 0.01 milligram per litre.
'The savings will be much greater as the worth of the metals alone could be well above the operating costs,' Professor Chan said.
Although the research focuses on precious metals, Professor Chan said there was good potential for recovering other heavy metals like cadmium.
Ocean Grand chairman Michael Yip Kim-po said the project could mean 'huge business opportunities'.